Cleaning apparatus and method utilizing pressurized water

ABSTRACT

A cleaning apparatus and method is disclosed which utilizes a nozzle generally comprising a cylindrical drum having external and internal air chambers, each of which terminates in a pipe having a rectangular cross-section. One of the pipes has a smaller cross-section than the other, and is disposed within the larger pipe. A high-pressure water pipe is concentrically disposed along the longitudinal axis of the smaller pipe. The space between the two pipes defines a passageway for a stream of compressed air which shapes the stream of water emanating out of the center of the smaller pipe into a jet of water having a bar-shaped cross-section, and a uniform pressure gradient at all points across this cross-section. The smaller pipe is provided with a symmetrical array of apertures for shunting part of the air stream flowing between the two pipes in a radial direction toward the pressurized stream.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method of usinghigh-pressure water to effectively wash facilities on an industrialfield, such as for example, the walls of tunnels under construction atroad sites. The invention makes use of a vehicle-mounted water sprayercapable of discharging pressurized water in a uniform, bar-shapedpattern.

The water sprayer of the invention ejects a bar-shaped water jet formedfrom uniformly pressurized streams of atomized water. The bar-shaped jetis formed by impinging a high-pressure stream of water with compressedair discharging through the walls of a rectangular nozzle and furtherimpinging said jet with other air flow by means of other instrumentsmounted on the moving vehicle.

Most conventional nozzles eject either elliptical, circular, orring-type patterns of liquid depending upon the shape and size of thedischarge port of the nozzle. Such an elliptical pattern is shown inFIG. 5. Here, the maximum pressure is located at the center portionthereof and becomes pregressively lower at the peripheral portion of theellipse, the further one gets from the axis O. The resulting variablepressure gradient is shown in FIG. 7. Such a gradient is present even inthose nozzles where the angle of the nozzle port is constructed to bevariable. The resulting pressure distribution pattern may be simplyrepresented as a series of isobaric electrical lines which resemblehills in a map (FIG. 8). Such a representation clearly demonstrates thata uniformless pressure is apt to occur particular in the direction ofthe Y axis of the ejection stream. Such non-uniformity compels theoperator to either excessively repeat the movement of the nozzle overthe structure being cleaned in order to obtain the desired washingeffect, or to use a plurality of nozzles.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus and method of washing roadfacilities, and generally comprises a cylindrical drum havig an externaland internal air chamber, each of which terminates in a pipe having arectangular cross-section. One of the pipes has a smaller cross-sectionthan the other, and is disposed within the larger pipe. A high-pressurewater pipe is concentrically disposed along the longitudinal axis of thesmaller pipe. The space between the two pipes defines a passageway for astream of compressed air which shapes the stream of water emanating outof the center of the smaller pipe into a jet of water having abar-shaped cross-section and a uniform pressure gradient at all pointsacross this cross-section. Preferably, the velocity of the stream ofcompressed air is approximately equivalent to the velocity of the waterjet leaving the water pipe. Additionally, the smaller pipe is providedwith a symmetrical array of apertures for shunting part of the airstream flowing between the two pipes in a radial direction toward thepressurized stream.

BRIEF DESCRIPTION OF THE SEVERAL FIGURES

FIG. 1 is a perspective view of a nozzle assembly embodying the presentinvention;

FIG. 2 is a top sectional view of this nozzle in operation;

FIG. 3 is a side sectional view of this nozzle in operation;

FIG. 4 is a graph illustrating the pressure distribution of the jetproduced by the nozzle of the invention;

FIG. 5 shows a conventional water distribtution pattern;

FIG. 6 is a graph representing the water pressure distribution patternof FIG. 4, and

FIGS. 7 and 8 show conventional water distribution patterns,respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention encompasses both a method of ejectinghigh-pressure water, as well as a nozzle for carrying out the method.The invention is particularly useful, when mounted on a travelingvehicle, for washing the wall surface of a tunnel. The nozzle of theinvention achieves a superior washing action by means of a jet of waterhaving a bar-shaped cross-section as shown in FIG. 6, which exerts auniform pressure on both the X and Y axes of the nozzle.

With reference now to FIGS. 1 and 2, the nozzle "I" of the invention isprovided with a first pipe 8 having a hollow rectangular sectionextending therefrom and a second pipe 9 having a smaller rectangularsection arranged within the rectangular section of the first pipe 8. Ahigh-pressure water pipe 4 which terminates in a tip 1 having a waterport 2 is centrally arranged within the rectangular section of thesecond pipe 9. Water port 2 is preferably elliptical in shape and lessthan 1 mm in diameter. Each of the pipes 8 and 9 are formed with an airflow passage 5 and 10 which communicates with a source of pressurizedair A to create a double layer of compressed air around the stream ofwater emanating from the water port 1. The nozzle "I" further includes acylindrical drum disposed at the back side thereof which is formed inpart by the rear walls of both pipes 8 and 9. The drum includes a first,annularly shaped air chamber 7 formed around the periphery of the drum,and a second circularly shaped air chamber 6 circumscribed by the firstchamber 7. The previously mentioned air port 10 places the two chambers6 and 7 into fluid communication, so that some of the compressed airentering the first chamber 7 via pipe 5 ultimately enters the chamber 6.A base 3 formed from a nut and threaded nipple arrangement supports thetip 1 of the high-pressure water pipe 4 which extends through the backof the drum of the nozzle and inside the second pipe 9.

With specific reference to FIGS. 2 and 3, the angle β shown in the topview of the nozzle "I" is preferably about 12.5° from the center line ofthe nozzle "I" to the inner surface of the smaller pipe 9, while theejection angle α is approximately 2° from the center line. The stream ofair a₁ flowing through the passage 7' defined between the larger pipe 8and the smaller pipe 9 diverges at least 7° from the plane defined bythe outer surface of the smaller pipe 9 and squeezes the jet of water W₂emanating from the tip 1 of the pipe 4. Preferably, the nozzle "I" is 65mm by 15 mm at its rectangular end, and 90 mm in depth according to theembodiment, and assembled by means of flanges 11 and 11' on both sides.

The nozzle "I" of the invention is operated in conjunction with anengine, a high-pressure pump and an air compressor (respectively notillustrated) loaded on a vehicle. Water W₁ at a pressure of 500 kg/cm²is fed to the charging pipe 4 and out of the water port 2. Thus, a waterflow W₂ is ejected frontward out of the elliptical port 2 as indicatedby the dashed lines. Simultaneously therewith, the greater portion a₁ ofthe compressed air flow A out of the charging pipe 5 is discharged intothe passage 7' from said first air chamber 7 of the drum at a speedwhich results in a flow rate of between 5 kg/cm² and 8 kg/cm², whichmakes its speed approximately equivalent to the speed of the ejectedwater flow 2. However, some of this compressed air flows through airport 10 into the chamber 6 and around the water flow W₂ in order toequalize the low pressure region created within the chamber 6 by theflow of pressurized water W₂. This low pressure region further shuntssome of the air flow a₁ of said passage 7' into the inside passage 6'through air passage holes 9',9' which slope downwardly through the wallof the pipe 9. Accordingly, the particles forming the flow W₂ arecollimated all the more in the direction of the vertical axis Y of thepassage 6'. The interaction of air flows a₁ and a₂ and the air flowthrough the holes 9' create a bar-shaped spray pattern which has aremarkably uniform pressure gradient across its X and Y axes. Thisuniform pressure grading is indicated by the solid lines in FIG. 4,which contrast favorably with the dotted lines which indicate thepressure gradients found in the water jets generated by prior artnozzles. The curve of a illustrated in FIG. 4 was attained by measuringthe pressure distribution pattern on the surface of an object to bewashed with respect to the above-mentioned function. Irrespective ofchanges in the operational distance, the curve of a on the surface waslogically long in the shape of a bar in the direction of the Y axis, andnarrow in the direction of the X axis. It is clear that the curves shownin FIG. 4 are equivalent to the flat pressure distribution curves ashown in the left sides of FIGS. 2 and 3.

An ejection water flow may produce the above-mentioned pressure patterna according to the method of the present invention, improving thestability thereof. Moreover, the particles forming the water flow do notnaturally diffuse an atomization, and accordingly, much dissipation ofthe energy is prevented.

It is to be understood that the action and effect in the presentinvention will not be limited to the embodiment mentioned above.

As a result of various experiments including applications in otherfields such as a painting works, it has been found that the ejectionwater flow W₂ may be controlled and adjusted quantitatively by therelationship between the number of holes forming the air passages 9',9'and the diameters thereof or the perforated angle thereof, or byadjusting the opening angle of the air passages when the pressure of thewater is selected in all particulars as desired within a range frombetween 100 kg/cm² and 1,000 kg/cm².

We claim:
 1. A nozzle for ejecting a jet of pressurized liquid having asubstantially uniform pressure gradient across its cross-section,comprising:(a) a first conduit and a second conduit which isconcentrically disposed within the first, whereby both conduits includean open end for forming and directing said jet, and a closed end forforming a first gas chamber which communicates with the space betweentwo concentrically arranged conduits, and a second gas chamber whichcommunicates with the interior of the second conduit; (b) a liquidconduit for discharging a stream of pressurized liquid through thesecond conduit toward its open end; (c) a compressed gas conduit fluidlyconnected to both said first and second gas chambers for providingstreams of gas both through the space between said conduits and throughthe interior of said second conduit which impinge with and shape saidstream of pressurized liquid, and (d) at least one aperture in the wallof said second conduit for conducting part of the stream of gas flowingthrough the space between said conduits into the second conduit in orderto shape said stream of pressurized liquid into said jet having auniform pressure gradient across its cross-section.
 2. The nozzle ofclaim 1, wherein said first and second conduits are pipes havingrectangular cross-sections at their open ends, and circularcross-sections at their closed ends, whereby the resulting jet of liquidhas a substantially bar-shaped cross section.
 3. The nozzle of claim 1,werein said second conduit includes a plurality of holes for forming asubstantially symmetrical array of gas streams around the stream ofpressurized liquid.
 4. The nozzle of claim 3, wherein the speed of thegas flowing through said space and through the interior of the secondconduit is selected so that it substantially matches the speed of thestream of liquid.
 5. The nozzle of claim 2, wherein said stream ofpressurized liquid is substantially aligned with the longitudinal axisof the second conduit.